Terror plot: The suspected bomb made it to check-in

NEW details have emerged about just how close alleged would-be bombers got to carrying an explosive device aboard an international flight from Sydney.

Earlier on Thursday, Sydney's Daily Telegraphreported an unwitting passenger may have been used to smuggle a bomb on board a plane destined for the Middle East.

The plot to have the device detonated "without (the bomber) knowing they were part of a suicide mission" was aborted.

On Thursday afternoon, Fairfax reported the device made it as far as Sydney International Airport terminal's check-in area and that a passenger was "queried about the weight of the luggage at the check-in counter and learnt it was too heavy".

The report suggests the bag was never checked in.

Neither NSW or Australian Federal Police would comment on the matter when contacted by news.com.au because the investigation is ongoing.

Australian intelligence received word last week about an apparent plan to smuggle an explosive onto a flight which led to dramatic raids over the weekend.

Police have remained tight-lipped about their investigations, however they are working with Etihad Airlines, who are assisting with inquiries.

On Tuesday, one of the four men arrested, Abdul Merhi, 50, was released without charge. Three other men remain in custody and have not been charged.

Abdul Merhi's lawyer Moustafa Kheir said his client felt he was "in a movie" when he heard of the allegations.

"It's a very serious allegation to have against you," Mr Kheir said. "It's just unfathomable that he would be associated­ with anything like this."

"He just wants to go back to as normal life as possible now," Mr Kheir said.

Police have called for photo identification to be reintroduced for issuing domestic plane tickets and for all airport employees to go through security screening.

The peak body for pilots has also called for greater security. AusALPA president Captain Murray Butt backed calls for all passengers to be required to produce photographic identification as they must in the US.

"We certainly don't want to alarm the public," he said in Sydney. "But we want to make sure we're providing the best service that we can and the safest service that we can."

Police are still searching properties in Lakemba, Wiley Park, Punchbowl and Surry Hills for evidence.

Prime Minister Malcolm Turnbull addressed the media on Thursday afternoon. He said the alleged plot was foiled but Australians should remain vigilant about the threat of an attack.

"The threat of Islamist terrorism is a global one," he said.

"As I've said many times, nowhere is far away from anywhere else in the age of the internet.

"Our enemies, those terrorists, those Islamist terrorist organisations are global and they are connected."

He also said there will be fewer delays at Australian airports for travellers after authorities disrupted the aviation terror threat. ASIO has moved to restore the aviation threat level to what it was before the alleged plot to bring down a plane was uncovered.

While there will be fewer flight delays, Mr Turnbull said it didn't mean people should become complacent.